NFPA 99 - Chapter 15 Warning Systems

  • Wednesday, October 29, 2025 7:43 AM
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    Message # 13557352
    Robert Kroening

    I am looking for clarification on how this group interprets this code Reference:

     

    15.4.2.10 Warning Systems (Oxygen and Nitrous Oxide).

    Category 2 warning systems shall comply with 5.2.9, except as follows:

    • (1) Warning systems shall be permitted to be a single alarm panel.
    • (2) The alarm panel shall be located in an area of continuous surveillance while the facility is in operation.
    • (3) Pressure and vacuum switches/sensors shall be mounted at the source equipment with a pressure indicator at the master alarm panel.

    I have interpreted this to mean that the single master alarm panel requires a sensor at the source equipment with its signal displaying the system pressure at the master alarm panel, and this sensor would alarm high and low at the master alarm panel.


    I have a gas equipment supplier that believes this to mean that a switch can be located at the main line near the source equipment, and a sensor installed downstream of the emergency shutoff valve that displays system pressure on the combination master/area alarm panel also meets this requirement.


    Let me know how you all interpret this code reference.
  • Thursday, October 30, 2025 7:32 AM
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    Reply # 13557825 on 13557352
    Mathis Carlson (Administrator)

    The way I read it, you need BOTH, but the pressure indicator (50 psi etc) is coming from the source location.


    Parens 3 states that you will have switches/sensors at the source equipment.
    Parens 7 says that you will have them after ANY valve including the emergency shut off valve.


    There is no OR, so all 8 subparagraphs apply.


    (7) Pressure switches/sensors shall be installed downstream of any emergency shutoff valves and any other shutoff valves in the system and cause an alarm for the medical gas if the pressure decreases or increases 20 percent from the normal operating pressure.


    Last modified: Thursday, October 30, 2025 7:35 AM | Mathis Carlson (Administrator)
  • Thursday, October 30, 2025 8:15 AM
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    Reply # 13557853 on 13557352
    Al Moon (Administrator)

    AMEN SECTION #7 IS THE ANSWER
  • Thursday, October 30, 2025 9:28 AM
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    Reply # 13557888 on 13557352
    Robert Kroening

    I am on board with these responses.

    This is also how we read the code.


    We were recently on a Dental facility, and the gas equipment supplier (one of the medical gas equipment suppliers) provided equipment and told us that they only needed a switch at the source (not providing a pressure display at the master from the switch) as long as they had the pressure displayed from the sensor downstream of the emergency shut-off valve.


    Thank you for confirming what I was thinking.

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